The wife of Jeff Bezos, the Amazon founder, could become the world’s richest woman if his fortune is split equally during their divorce proceedings.

Bezos, 54, and wife MacKenzie, 48, announced yesterday that, following a trial separation, they had decided to end their marriage of 25 years.

Their divorce settlement is likely to be the most expensive in history and may reshape global wealth rankings. The Daily Beast is reporting that there was no prenuptial agreement in place, and that Bezos is already dating again.

Having started Amazon from his garage in Seattle, Bezos went on to become the richest man on the planet, with an estimated fortune of US$137 billion.

As well as his shareholding in Amazon, Bezos owns the Washington Post newspaper as well as a string of other investments including a Gulfstream jet and homes in Seattle, Washington, Beverly Hills and New York.

If the couple file for divorce in Washington, the state where they were married and Amazon has its headquarters, half of Bezos’s wealth could go to his wife under the state’s community property law, unless there is a prenuptial agreement in place.

If they split their fortune equally, it could leave Mackenzie Bezos with around US$69 billion, making her the world’s richest woman. It could also reinstate Bill Gates, the co-founder of Microsoft, as the world’s richest person.

Jeff Bezos, founder and chief executive officer of Amazon.com Inc., and his wife MacKenzie Bezos, arrive for morning sessions at the 28th annual Allen and Co. Media and Technology Conference in Sun Valley, Idaho on Saturday, July 10, 2010.Matthew Staver/Bloomberg

In a statement the couple, who have four children together, said: “As our family and close friends know, after a long period of loving exploration and trial separation, we have decide to divorce and continue our shared lives as friends.

“We feel incredibly lucky to have found each other and deeply grateful for every one of the years we have been married to each other.”

The pair added: “If we had known we would separate after 25 years, we would do it all again.”

In an interview with Wired in 1999, Bezos described his search for his ideal mate. Calling himself a “professional dater,” he devised a system to filter potential partners. “The number-one criterion was that I wanted a woman who could get me out of a Third World prison,” he told the website. “What I really wanted was someone resourceful. But nobody knows what you mean when you say, ‘I’m looking for a resourceful woman’.”

As it happened, Bezos fell in love with a member of his own staff while working at a New York hedge fund. They were married in 1993, six months after they began working together, and a year before he started Amazon.

MacKenzie Bezos, an award-winning novelist in her own right, was one of Amazon’s earliest employees and became an accountant for the business.

The news of their divorce emerged two days after Amazon became the world’s most valuable company, overtaking Microsoft.

Last year, the couple launched a $2 billion charitable fund, called the Day One Fund. Their joint statement, released on Bezos’s twitter account yesterday, suggested they would continue to collaborate on the project.

“Though the labels might be different, we remain a family, and we remain cherished friends,” the couple added.

David Starks, a divorce attorney at the Washington law firm McKinley Irvin, said: “There’s reasons to believe they’d go ahead and do their divorce here in Washington. [The state] follows the old regime of community property… all assets that are accumulated during a marriage are presumed to be community.” If the couple did not come to their own agreement, a judge would probably divide their assets equally, he said.

“When we’re talking about ludicrous amounts of money… if we’re speculating what a judge would do, we’re talking 50-50.”